Any discussion of the prior art throughout the specification should in no way be considered as an admission that such prior art is widely known or forms part of common general knowledge in the field.
Environmental concerns and the awareness of the finite resources of traditional combustible hydrocarbon fuel sources has lead to research into sustainable non-polluting energy sources such as waves, wind, tidal, geothermal and solar.
Numerous different types of wave power generation systems have been proposed. One system employs the basic principle of using the vertical motion inherent in the movement of waves to effect a rotary movement of a turbine to drive directly or indirectly a generator to produce electricity. In such systems, there is frequently reversing air flow conditions present, caused by the oscillatory motion of the waves. A number of specially configured unidirectional turbines have been designed to allow the turbine to continue operating in response to such reversing air flow conditions.
However, many, if not all, of these prior systems operate at a relatively low efficiency due to losses in the system when converting the oscillatory motion of the waves into rotational mechanical energy.
In addition, many prior wave power generation systems are heavily reliant upon the direction of travel of the prevailing ocean wave. Furthermore, many existing wave power generation systems are moored to constantly face in one direction and therefore operate below optimum efficiency for long periods due to changes in wave direction arising from natural tidal changes.
Another disadvantage of many known wave power generation systems operating on the basic principle of using the vertical motion of waves to effect rotary movement of a turbine which in turn drives a generator to produce electricity is that these systems commonly rely on the principle of gravity-induced resonant amplification to ensure efficiency of operation to attain the desired levels of power output. In such systems, it is necessary to convert the oscillatory motion of the water to an airflow. That is, many currently known systems typically require a hydraulic to pneumatic conversion process, further reducing the efficiency of the total energy conversion process.
In addition, many known wave power generation systems must be built to withstand the large and unpredictable forces to which they are subjected from ocean waves. To ensure the sustainability of a system over its working life a level of redundancy is required to be built into the system. For example, ocean power generating systems are commonly required to withstand the forces associated with the large waves of “once in a hundred year storms”. The magnitude of the forces in these extreme cases is many times that of the forces arising in most storms and, as such, significant additional costs are necessarily incurred when manufacturing, installing and maintaining the system. It has been found that these additional costs are often so high that they can render systems commercial unviable.
Systems built to withstand the most extreme forces are necessarily larger in size and, consequently, the visual appeal of these systems is reduced. The visual appeal or aesthetics of sustainable energy systems such as ocean wave energy extraction systems is an important factor, not only for reducing the visual impact on the surrounding environment, but also for gaining public acceptance of these alternative means of producing energy.
It is an object of the present invention to overcome or ameliorate one or more of the disadvantages of the prior art, or at least provide a useful alternative.